Question

Calculate number of atoms is each of
the following. (Average atomic mass :
N = 14 u, S = 32 u)
a. 0.4 mole of nitrogen
b. 1.6 g of sulfur
​

Answer 1

Answer:

Explanation:1 moe of N2 is having 2N atom then 0.4 moles of N2 has 4/10*2N atoms =4.8*10^23

32 gms of S contains 1N atoms then 1.6 gms contain 1/20N atoms = 3.01*10^23

Answer 2

a. Here, it means that -

0.4 mole = 14 u

So,

$1 \: mole \:  =  \frac{14}{0.4}$

Hence, to find the number of atoms, we have to now multiply the mole that we have got with the Avogdro's number.

So,

$number \: of \: atoms \:  =  \frac{14}{0.4}  \times 6.022 \times  {10}^{23}$

  =

$210.77 \times  {10}^{23}  \: atoms$

Hence, this is the number of atoms found in 0.4 mole of nitrogen.

b. 1.6 g of sulfur

First, we have to find the number of moles in 1.6 g of sulfur. To calculate the mole number, we have to apply this formula -

$moles \:  =  \frac{given \: mass}{molar \: mass}$

$n \:  =  \:  \frac{1.6}{32}$

n = 51.2 mol

So, number of atoms will be -

$1.2 \times 6.022 \times  {10}^{23}$

$72.6 \times  {10}^{23} atoms$

Hence, this is the number of atoms present in 1.6 g of sulfur.